Question

I am programming an AVR microcontroller, and in the programmers notepad in the WINAVR Suite.

I am trying to seperate my code, however the sepeaet .c file I am unable to use AVR pre-defined variables. (the variables AVR supplies to point to certain BITs)

for example,
this code will work in my main.c file. but not in another random.c file:

 UBRR0H = (unsigned char)(ubrr>>8);

it gives the error :

random.c:6: error: 'UBRR0H' undeclared (first use in this function)

in my main.c file it only has the following includes:

#include <stdio.h>
#include <stdlib.h>
#include <util/delay.h>
#include <string.h>
#include <avr/interrupt.h>
#include "lcd.h"
#include "random.h"

Answer 1

You have to create file like yours.h, where you put or your function definitions and macros definitions:

#define UBRR0H (unsigned char)(ubrr>>8);

int mine_function( char, char, int);

...

extern int global_variable;

_{not sure whether UBRR0H is macro or extranal variable}

In addition use something about extern variables and some articles about how to use them.

And than in every your .c file you should:

#include "yours.h"

If you get in troubles because you’ll end up with many .h files and you’ll be including the same thing multiple times (will cause error, previously defined there), there easy hack, in yours.h:

#ifndef _H_YOURS_INCLUDED_
#define _H_YOURS_INCLUDED_ 1

// Your real content

#endif /* _H_YOURS_INCLUDED_ */